The present invention relates to an apparatus and method for checking paging information transmitted in a Personal Handyphone System (PHS), and in particular, to an apparatus and method for reducing power consumption by a PHS portable station when checking paging information.
Cellular telephone communications systems allow users to communicate via portable stations or handsets without the use of a wire or cable connection. Voice and data is transmitted in cellular telephone technology through radio waves at a particular frequency. By eliminating the need for a hard-wire connection, cellular telephones can be used, for example, in a car or on an airplane. The increased use of cellular telephones in recent years is due in large part to this mobile feature.
There are various cellular telephone services under which cellular telephones operate. One system is the Personal Handyphone System (PHS). The PHS is a high capacity fully digital mobile cellular telephone service that was originally launched in Japan in 1995. Like other cellular telephone services, the PHS has its own operation standard governing the use of radio facilities and equipment that transmit over radio waves within the system.
A desirable feature for any cellular telephone is a handset that is sized to allow it to be easily managed and transported. For example, it is preferable to provide a handset with an overall size that can be carried in a handbag, such as a purse, or a pocket of a jacket.
One of the components of a handset that significantly affects the overall size of the handset is the battery. The battery is removably attached to the handset to provide power needed to operate the handset. When power is depleted from the battery, it is removed and recharged or replaced with another battery. While a smaller battery may be preferred for convenient transporting of the handset, a smaller sized battery compromises the amount of power that the battery provides to the handset between charges.
A typical handset continuously drains power from the battery when the handset is in a standby mode or is otherwise processing control information associated with a data transfer to the handset. During standby, the handset's processor continually receives and processes packets of control information unique to particular data transfers. The control information may include the identification numbers of the called handset, the calling handset, and the base station that facilitates the transmission between the called handset and the calling handset. Moreover, the control information may identify the attributes or the type of data that is being transmitted. By processing the control information during standby, a handset determines, for example, if it is the called station. If so, a communication link is initiated to the calling station. Similarly, once a communication link is established, the handset continues to process control information relating to that data transfer. Not surprisingly, the processing of control information at the handset's processor draws considerable power from the battery. In turn, this limits the length of time for which a handset can operate with a given battery.
A possible solution to the problem of power consumption is to increase the size of the battery or to carry one or more spare batteries to replace a depleted battery. Both of these options, however, minimize the mobility advantages offered by cellular telephone technology as it increases the size of the handset or the number of components that are needed to operate the handset.
Based on the foregoing, it can be seen that a tension exists between providing a conveniently-sized cellular telephone handset and the desire to reduce power consumption of the handset to increase the period of time between charging.